Mathematics 2016 Jamb Examination
Mathematics 2016 Jamb Examination
Question 21
Simplify \( \dfrac{0.026 \times 0.36}{0.69} \). Leave your answer in standard form.
First, perform the multiplication in the numerator: \[ 0.026 \times 0.36 = 0.00936 \] Next, divide by the denominator: \[ \dfrac{0.00936}{0.69} \approx 0.013565... \] Rounding to three significant figures gives \( 0.0136 \). In standard form (scientific notation): \[ 1.36 \times 10^{-2} \]
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Question 22
A number of pencils were shared out among Bisi, Sola and Tunde in the ratio of 2:3:5 respectively. If Bisi got 5, how many were shared out?
The ratio is 2:3:5. Let the total number of pencils be \( x \). Bisi's share is represented by 2 parts out of the total 10 parts \( (2+3+5) \).
\[ \dfrac{2}{10} \times x = 5 \]
\[ \dfrac{1}{5}x = 5 \]
\[ x = 5 \times 5 = 25 \]
Total pencils shared were 25.
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Question 23
Calculate the perimeter of a sector of a circle of radius 9cm and angle 36°.
The perimeter of a sector is the sum of two radii and the arc length:
\[ \text{Perimeter} = 2r + \left( \dfrac{\theta}{360} \times 2\pi r \right) \]
Substituting \( r = 9 \) and \( \theta = 36 \):
\[ \text{Perimeter} = 2(9) + \left( \dfrac{36}{360} \times 2\pi(9) \right) \]
\[ \text{Perimeter} = 18 + \left( \dfrac{1}{10} \times 18\pi \right) = 18 + \dfrac{9\pi}{5} \; \text{cm} \]
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Question 24
Evaluate \( \dfrac{27^{1/3} - 8^{2/3}}{16^{2/4} \times 2} \)
Simplify each part using indices rules:
\[ 27^{1/3} = \sqrt[3]{27} = 3 \]
\[ 8^{2/3} = (\sqrt[3]{8})^2 = 2^2 = 4 \]
\[ 16^{2/4} = 16^{1/2} = \sqrt{16} = 4 \]
Substitute back into the expression:
\[ \dfrac{3 - 4}{4 \times 2} = \dfrac{-1}{8} \]
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Question 25
Scores: 3, 6, 5, 2 | Frequency: 2, 3, 4, 6. From the table, find the median.
First, arrange the scores in ascending order with their frequencies:
Score 2 (Freq 6), Score 3 (Freq 2), Score 5 (Freq 4), Score 6 (Freq 3).
Total frequency \( N = 15 \). The median is the \( \frac{15+1}{2} = 8^{\text{th}} \) value.
Cumulative frequencies: 6, 8, 12, 15. The \( 8^{\text{th}} \) value falls in the 'Score 3' group.
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Question 26
Find \( \dfrac{dy}{dx} \), if \( y = \dfrac{2}{3}x^3 - \dfrac{4}{x} \)
Rewrite the function: \( y = \dfrac{2}{3}x^3 - 4x^{-1} \). Differentiate using the power rule: \[ \dfrac{dy}{dx} = \dfrac{2}{3}(3x^2) - 4(-1x^{-2}) \] \[ \dfrac{dy}{dx} = 2x^2 + 4x^{-2} = 2x^2 + \dfrac{4}{x^2} \]
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Question 27
Evaluate \( \dfrac{0.8 \times 0.43 \times 0.031}{0.05 \times 0.72 \times 0.021} \). Correct to four significant figures.
Calculate numerator and denominator:
\[ \text{Numerator} = 0.010664 \]
\[ \text{Denominator} = 0.000756 \]
\[ \dfrac{0.010664}{0.000756} \approx 14.10582... \]
To four significant figures, we get 14.11.
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Question 28
An arc subtends an angle of 30° at the centre of a circle radius 12cm. Calculate the length of the arc.
Use the formula for arc length \( L \):
\[ L = \dfrac{\theta}{360} \times 2\pi r \]
\[ L = \dfrac{30}{360} \times 2\pi(12) = \dfrac{1}{12} \times 24\pi = 2\pi \; \text{cm} \]
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Question 29
Evaluate \(\displaystyle \int_{0}^{\pi/2} \sin x dx \)
Integrate \( \sin x \) to get \( -\cos x \): \[ \int_{0}^{\pi/2} \sin x dx = [-\cos x]_{0}^{\pi/2} \] \[ = -(\cos(\pi/2) - \cos(0)) \] \[ = -(0 - 1) = 1 \]
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Question 30
An arc of the length 16π cm subtends an angle of 80° at the centre of the circle. Find the radius of the circle.
Using the arc length formula:
\[ L = \dfrac{\theta}{360} \times 2\pi r \]
\[ 16\pi = \dfrac{80}{360} \times 2\pi r \]
\[ 16 = \dfrac{160}{360}r \Rightarrow 1 = \dfrac{10}{360}r \]
\[ r = \dfrac{360}{10} = 36 \; \text{cm} \]
